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1Symposium 10yrs PTL, Vitznau, 05. July 2008
Flame Aerosol Synthesis
From Lab-Scale Experiments to Pilot Plant Production
Karsten WegnerWegner Consulting & ETH Zürich
2Symposium 10yrs PTL, Vitznau, 05. July 2008
How everything started...
Prototype diffusion flame microreactor
Material: copper, welded
Fabrication: hand-made in Cincinnati (OH)
Characteristics: 6 “concentric” tubes 1/10”, 1/6”, 7/32”, ...
3Symposium 10yrs PTL, Vitznau, 05. July 2008
The Swiss response:
Diffusion flame microreactor
Material: stainless steel 1.4435
Fabrication: machined at ETH workshop
Characteristics: 6 concentric! tubes: 2.54mm, 4.23mm, 5.56mm,...
4Symposium 10yrs PTL, Vitznau, 05. July 2008
Flame aerosol synthesis set-up
Precursor
Reaction
Collision
Sintering
Product
Collection
5Symposium 10yrs PTL, Vitznau, 05. July 2008
The first nanoparticles at ETH-PTL
Oxygen Flow Rate, L/min0 2 4 6 8 10B
ET-
equi
vale
nt P
artic
le D
iam
eter
, nm
0
20
40
60
80
100
~5 g/h silica from hexamethyldisiloxane (HMDSO)
6Symposium 10yrs PTL, Vitznau, 05. July 2008
Early pilot-scale production
0
10
20
30
40
0 200 400 600 800
Production rate, g/h
Prim
ary
part
icle
dia
met
er,
0.0
0.5
1.0
1.5
0 20 40 60 80 100
SiO2 mass concentration, g/m3
Car
bon
cont
ent,
wt.%
Hydrogen-oxygen diffusion burner obtained from German Aerospace Research Center (DLR)
Kammler, Mueller, Senn, Pratsinis, AIChE J. 47, 1533 (2001)Kammler, Mädler, Pratsinis, Chem. Eng. Technol. 24, 583 (2001)
7Symposium 10yrs PTL, Vitznau, 05. July 2008
Burner Operation Lines
Oxygen Flow Rate, L/min0 10 20 30 40 50B
ET-
equi
vale
nt P
artic
le D
iam
eter
, nm
0
20
40
60
80
100
Burner 123
Conditions:
CH4: 0.5 L/min
Ar: 0.3 L/min
SiO2: 5 g/h 27 mm
10 mm
6 mm
Wegner and Pratsinis, Chem. Eng. Sci. 58, 4581 (2003)
8Symposium 10yrs PTL, Vitznau, 05. July 2008
Ar/Prec.
CH4
O2
Coaxial Jet MixingDiffusion Flames:
treaction << tmixing
Particle Formation upon mixing of precursor and oxidant at shear layer.
Similar reactant mixing for similar velocity difference Δv = vOx - vFuel
vAr+Prec. ≈ vCH4 ≤ vOx
vFuel
Cold flow CFD profiles: Ar concentration
9Symposium 10yrs PTL, Vitznau, 05. July 2008
Single Operation Line dp = f(Δv)
Δv = vOx - vFuel, m/s
0 5 10 15 20 25 30
BE
T - e
quiv
alen
t Par
ticle
Dia
met
er, n
m
0
20
40
60
80
100
Burner 123
Silica
10Symposium 10yrs PTL, Vitznau, 05. July 2008
Δv = vOx - vFuel, m/s
0 5 10 15 20BE
T-eq
uiva
lent
Par
ticle
Dia
met
er d
p, nm
0
20
40
60
80
100
120 5 g/h SiO215 g/h25 g/h
dp,i = d0,i + (dm,i - d0,i) exp ( - 0.3 Δv)
Scaling the SiO2 Production Rate
Wegner and Pratsinis, Chem. Eng. Sci. 58, 4581 (2003)
Increase of CH4, Ar, and HMDSO flow rates
11Symposium 10yrs PTL, Vitznau, 05. July 2008
Products of Conventional Flame ProcessesH He
Li Be B C N O F NeNa Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I XeCs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At RnFr Ra Ac Unq Unp Unh Uno Une
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb LuAc Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Few metal oxides accessible due to limited availability of low-cost precursors with high vapor pressure at moderate Temp.
At ETH-PTL: SiO2, TiO2 - but also first flame-made catalysts: vanadia/titania at small and pilot scale.Stark, Wegner, Pratsinis, Baiker, J. Catal. 197, 182 (2001)Stark, Baiker, Pratsinis, Part. Part. Sys. Char. 19, 306 (2002)
12Symposium 10yrs PTL, Vitznau, 05. July 2008
vacuum pump
burner chamberwith filter
precursor
OFIC
2
4CH
O or air
2
FICFIC
FIC
flamelet ring
spray flame
PI
syringepump
M
FIC
FICOsheath flow
2
nozzlecooling (H O)
FIC
2
capillarycooling (H O)
gas exit gap
heatedbox
22
2
Mädler, Kammler, Mueller, Pratsinis, J. Aerosol Sci. 33, 369 (2002). Liquid 2O2O 4CH
Flame Spray Pyrolysis (FSP) Technology
13Symposium 10yrs PTL, Vitznau, 05. July 2008
Accessible Products by FSP
Noble metals and oxides of almost all periodic table elements
Flame synthesis using vaporous precursors
H HeLi Be B C N O F NeNa Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I XeCs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At RnFr Ra Ac Unq Unp Unh Uno Une
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb LuAc Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
14Symposium 10yrs PTL, Vitznau, 05. July 2008
Benefits of the FSP ProcessBroad range of product materials
Multi-component particles
Good control of particle properties
High purity powders
Thermally stable powders
Environmentally friendly process
Short process chain
Standard equipment and materials
Low cost energy source
Recent review article: Strobel and Pratsinis, J. Mater. Chem. 17, 4743 (2007).
15Symposium 10yrs PTL, Vitznau, 05. July 2008
Scale-up from 10 to ~500 g/h
ETH Pilot SystemZÜNDENDE PROJEKTE FÜR MASSGE-SCHNEIDERTE NANOPARTIKEL.
JAHRESBERICHT 2003
ETH Lab-Scale
Mueller, Mädler, Pratsinis, Chem. Eng. Sci. 58, 1969 (2003).Mueller, Jossen, Pratsinis, J. Am. Ceram. Soc. 87, 197 (2004).
16Symposium 10yrs PTL, Vitznau, 05. July 2008Tokyo Nanotech 2008
17Symposium 10yrs PTL, Vitznau, 05. July 2008
Process Flow Diagram
18Symposium 10yrs PTL, Vitznau, 05. July 2008
1 kg/h Pilot Plant at FlamePowders
5 kg ZnO nanoparticles
19Symposium 10yrs PTL, Vitznau, 05. July 2008
Process Design Considerations
Filtration area?Flow fieldNanopowder dischargeOff-gas treatmentProduct or clean sidefilter change?Product change?Containment! Safety!
FilterReactantDelivery FSP Reactor
Chemicals used?Batch/continuous?Precursor preparation?Precursor stability?Quality control?Cleanability?Safety!
Flow-/production rates?Auxiliary gases?Stability of combustion?Process Control?Energy utilisationCO2 reductionContainment!Safety!
Nanoparticle containment and safety concept.Process automatization
Product specs., production rate, raw materialsPurity requirementsAvailable infrastructure
20Symposium 10yrs PTL, Vitznau, 05. July 2008
100 g/h Pilot Plant for NanoCentral
Location: Johnson Matthey Research Center, UK www.nanocentral.eu
21Symposium 10yrs PTL, Vitznau, 05. July 2008
Automated FSP Unit at L’Urederra
Production rate 0.5 – 1.0 kg/h, continuous operationProcess control by PLC
Fundación L’UrederraLos Arcos (Navarra), Spain
22Symposium 10yrs PTL, Vitznau, 05. July 2008
Under construction: 1 kg/h unit
23Symposium 10yrs PTL, Vitznau, 05. July 2008
Back to the small scale:Combined FSP-cluster beam deposition
Aerodynamic lens system
Skimmer
Depositionchamber
Expansionchamber
Vacuum systeminlet
Interfacechamber
Aerodynamic lens system
Skimmer
Depositionchamber
Expansionchamber
Vacuum systeminlet
Interfacechamber
1 μm1 μm Patterned deposition
Nanostructured particulate films
24Symposium 10yrs PTL, Vitznau, 05. July 2008
Thank you very much! Questions?
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